Sealing device



June 1959 L. B. ROCKLAND ETAL 73 SEALING DEVICE 2 Sheets-Sheet 1 FiledOct. 24, 1955 1.. B. ROCKLAND L F ATKINSON INVENTORS AT 0 NEYS O & NN

,June 9, 195 B; ROCKLAND EI'AL 2,889,673

SEALING DEVICE Filed Oct. 24, 1955 2 Sheets-Sheet 2 FIG. 2 I FIG-5 l4a23 I40 I4 4 B, ROCKLAND L. F. ATKINSON INVENTORS SEALE IG DEVICE LouisB. Rocklaud, Pasadena, and Lawrence F. Atkinson, Arcadia, (ladilf.assignors to the United States of America as represented by theSecretary of Agriculture Application October 24, 1955, Serial No.$42,532

2 Claims. (Ci. 53-412) (Granted under Title 35, US. Code (1952), sec.266) A non-exclusive, irrevocable, royalty-free license in the inventionherein described, throughout the world for all purposes of the UnitedStates Government, with the power to grant sublicenses for suchpurposes, is hereby granted to the Government of the United States ofAmerica.

This invention relates to sealing devices particularly adapted to thesealing of containers made of plastic films or other sheet material. Aparticular object of the invention is the provision of novel equipmentof such type by which containers can be evacuated, or invested with anydesired fluid, prior to sealing. Further objects and advantages of theinvention will be obvious from the follow ing description taken intoconnection with the annexed drawing.

In the drawing:

Figs. 1, 2, and 3 are elevations of one modification of the sealingdevice falling within the scope of this invention. The separate Figures1, 2 and 3 depict the same device in three phases of operation: Fig. 1illustrates the device open for insertion of a container; Fig. 2illustrates the device in the vacuumizing phase; and Fig. 3 illustratesthe device in the sealing phase. In Figs. 2 and 3 parts have beenomitted to simplify the representation.

Figs. 4, 5 and 6 represent, respectively, a side elevation of theevacuating tube, a cross-section taken on plane A-A' of Fig. 2, and aplan view of the bag-tensioning device. All of these figures are on anenlarged scale.

Within recent years there has been a trend toward increased use ofcontainers made of plastic films for packaging various products. Withmany types of articles such containers are quite satisfactory and oftencheaper and more attractive than conventional containers of metal orpaper. In some instances it is desirable to package materials undervacuum or in an atmosphere of an inert gas. Such type of packaging isdesirable for example with foodstufis which are susceptible to oxidativechanges on storage. Examples of such foods are nuts, bacon, ham, andmany other meat products, dehydrated fruit or vegetable juices,dehydrated potatoes, dehydrated soups, coffee, and so forth. Equipmenthitherto available for such packaging purposes is complex, expensive andslow in operation. For instance, the generally used sealers are of whatmay be termed the cavity type. These devices include a cylinder equippedwith a removable lid. The bag containing the material to be packaged isplaced in the cylinder, the lid is secured, and all the air in thecontainer is exhausted. The package is sealed while in the cylinder,then the lid is opened and the sealed package removed. Such equipmenthas the primary disadvantage that all the air in the cylinder must beavacuated to achieve vacuum Within the package. This is naturally acumbersome technique and the packaging operation is slow because of thisfact. Where the package is to be invested with an inert gas, there isconsiderable wastage of such gas as the entire cylinder must be filledwith the gas.

One significant feature of the device of this invention is that only theair in the package itself need be exhausted connected to a source ofvacuum (not illustrated).

to achieve sealing under vacuum. This means that the device of thisinvention can utilize a vacuum pump of smaller size and the attainmentof vacuum requires less time because there is much less volume of air tobe removed. Where an inert gas or other fluid is to be intro duced intothe package after evacuation, only that amount of gas which is actuallyneeded in the package is used.

The principles of the invention are explained as follows:

Fig. 1 illustrates the sealing device in its open position for receptionof a package to be sealed. The device includes fixed jaw 1 and movablejaw 2. I aw 2 is adjustably attached by screws 2a to plates 3 which inturn is attached to shaft 3a. This shaft extends through packing gland 4into cylinder 5, there being a piston 8 attached to shaft 3a withincylinder 5. At the opposite ends of cylinder 5 are provided pipes 6 and7, these being connected to a conventional pneumatic pumping system (notillustrated). It is evident that by forcing the air into pipe 6 andwithdrawing the air through pipe 7, jaw 2 can be moved away from jaw 1.By reversing the flow of air, jaw 2 can be moved toward jaw 1. Jaws 1and 2 are preferably made of aluminum, brass or other electricallyconductive metal in the modification in which the bags are electricallysealed, that is, by applying a high frequency current across the bag atthe point of sealing. If scaling is to be carried out by thermal means,

that is, by applicationot a heated blade to the bag, then the jaws may.be constructed of strong, heat-insulating material. Where the jaws aremade of metal their inner tapes may be covered with an electricallyinsulating material to prevent accidental shock to the operator.

The means for pinching shut the open end of a bag during evacuation andsealing includes boss 9 mounted on jaw 1, this boss being covered withpad in made of rubber or other flexible material. Cooperating with thesemembers and located on jaw 2 is arm 11 covered by rubber pad 12. Arm 11is slidably received in horizontal slot 13 so that the arm can movetoward or away from jaw 1 in a horizontal plane. A series of springs 14adapted to exert an outward bias (toward jaw ll) against arm 11 isprovided within slot 13. Arm ill is provided with bolts 14a which act aslimit of motion devices to prevent springs 14 from ejecting the arm itout of slot 13. i The means for sealing the bag includes anvil 15protruding from the face of jaw i. This anvil is metallic for use withan electronic sealing blade or is made of silicone rubber, for example,for use with a heat sealing blade. Cooperating with anvil 15 is metallicsealing blade 16 carried by jaw 2. The sealing blade illustrated has adouble bag-contacting head and will establish a double seam of sealingacross the mouth of the bag. Blades for forming a single seam or morethan two seams may be used 'as desired. Sealing blade 16 may beexchanged for another of different shape by sliding it out of keyway 17.

A suitable generator of high-frequency electromagnetic waves (notillustrated) is connected via wires 13 and 19 to jaws 2 and 1,respectively. When the generator is actuated, the current will fiowthrough the container to be sealed at the area of contact between anvill5 and blade 16 causing the sides of the container to be fused together.

The means for withdrawing air from packages and for introducing desiredfluid into the packages after evacuation is described as follows:

Upon jaw 1 is mounted bracket 21 to which is pivoted arm 22 which bearstube 23. Spring 23a biases tube 23 away from jaw 1 when the jaws areopen. Tube 23 is If desired a series of valves may be provided forserial connection of tube 23 with a source of vacuum, then with a sourceof inert gas or other fluid desired for intro duction into the package.

The lower portion of tube 23 is flattened as at 24. About the flattenedportion is provided a rubber winglike member 25, see Figs. 4 and 5. s

Referring now to Fig. 4, it is seen that 'tube 23 connects with barrel26 provided with perforations 27. The ends of barrel 26 are providedwith generally acornshaped cages 28, the diameter of these beingsomewhat larger than the diameter of barrel 26. Air or other fluid canpass freely through perforations 27 into tube 23 or through apertures 29into the open ends of barrel 26 and thence into tube 23.

The bag tensioning or flattening device is depicted in Fig. 6. Referringto this figure, on jaws 1 and 2 are provided bosses 30 and 31,respectively, made of strong, non-conductive plastic material whichcarry pivots 32 and 33 which in turn bear rubber-covered steel springbars 34 and 35. Bearing against bars 34 and 35 are coil springs 36 (onlyone illustrated) set in recesses 37. Springs 36 tend to force bars 34toward bars 35. When the sealing device is in the vacuurnizing phase(Fig. 2) the bars 34 and 35 press against the container with minimumforce and therefore do not cause the bag to be pinched shut wherebythere is no interference with the evacuation of air from within thecontainer. However, when the sealing device is in the sealing phase(Fig. 3), the bars 34 and 35 exert a sideward pressure on the containeras the jaws 1 and 2 come together. The side ward stretching of thecontainer prevents crimping at the seal and hence prevents inefiectiveclosure.

In operating the device to seal a package, the jaws are open as in Fig.1 and tube 23 is pivoted away from jaw 1 also as shown in this figure. Abag 40 of polyvinylidene chloride film or the like containing articles41 is inserted between the jaws to envelop the lower part of tube 23.

The pneumatic system is then actuated to move jaw 2 to the left to theposition shown in Fig. 2. At this stage, the power exerted by thepneumatic system is so balanced against the expansive bias of springs 14that pads 10 and 12 are in tight engagement whereas anvil 15 and sealingblade 16 are a small distance apart. The engagement of pads 10 and 12causes a closing of the open end of bag 40 so that the bag can then beevacuated.

After, or simultaneously with, the closing of jaw 2, tube 23 isconnected to the source of vacuum. As the air is sucked out of bag 40,the walls of the bag collapse. However, barrel 26 and cage 28 preventthe collapsing walls of the bag from plugging up the passageway to tube23. The perforations 27 permit the vacuum to hold the side walls of thebag close to the barrel 26 and aid in preventing the plastic film frombeing stretched and pulled into apertures 29. The tension bars 34 and35, the bag mouth pinching assembly (members 9, 10, 13, 14, etc.) allaid in preventing extension of the plastic film and the collapse of thefilm which otherwise would tend to seal off apertures 29 and preventevacuation of the bag. With the device of this invention, the residualair in bag 40 can be evacuated within a few seconds.

Referring to Fig. it can be seen that during the evacuation and sealingphases, no air can get into the bag 40. Thus it is squeezed shut betweenpads and 12. During these phases the pressure forcing jaws 1 and 2together also causes pads 10 and 12 to deform about wing-like member 25so that no air can leak in about the flattened portion 24 of tube 23 orabout the sides of the wing 25. The boss 9 and arm 11 are recessedslightly as at 42 and 43 to permit deformation of rubber pads 10 and 12to conform to the shape of the wing member 25 and tube 24.

It is obvious that the members 9 and 10, 11 and 12, and 16, and 34 and35 should have a length (the dimension running at right angles to thepaper on which 4 Figs. 1, 2 and 3 are drawn) greater than the width ofbag 40. On the other hand, wing 25 should be of less width than the bagso that the bag can easily be placed about wing 25 when the packagingoperation is initiated.

After the bag 40 has been exhausted, the air pressure in the pneumaticsystem connected to tube 7 is increased to increase the pressure on theright hand side of piston 8 in order to overbalance the expansive forcesof springs 14 bearing against arm 11 and springs 36 hearing against bars34, 35. As a result, anvil 15 and sealing blade 16 bear against thewalls of bag 40 extending between them, as shown in Fig. 3. At this timethe source of electrical energy connected to wires 18 and 19 is turnedon and as a result of the heating effect taking place at the point ofcontact the bag is sealed along parallel seams corresponding with thelength of blade 16. During the sealing operation springs 34 and 35stretch the walls of bag 40 to prevent crimping as explained above.

After the sealing has been completed, the hydraulic system is activatedto move piston 8 to the right whereby the sealed bag 40 is released anddrops out from between jaws 1 and 2. The device is then ready forsealing up the next package.

If the package is to be invested with a fluid prior to sealing, thefollowing technique is applied. Bag 40 is exhausted as previouslydescribed then tube 23 is connected with a source of fluid to introducethis material into the bag. Jaw 2 is then moved further to the left tocause engagement of the sealing anvil and blade (15 and 16) and thesealing is efi'ectuated as before.

Introduction of an inert gas, such as nitrogen, into the container afterevacuation and prior to sealing is often desirable with diverse foodproducts to protect them from oxidation, etc. during storage. Also byintroducing a gas of this type the particles 41 will be loose within thepackage after sealing. If the package is sealed under vacuum the wallsof bag 40 will remain tightly collapsed about the particles 41 so thatthe package will be a rigid unit and particles 41 will be held tightlytogether by the pressure of the atmosphere acting on the external wallsof bag 40. Thus there is a matter of appearance to be considered here asto Whether the final package is desired to be limp and contain loosearticles (sealed in gaseous atmosphere) or Whether the final package isdesired as a rigid unit with coherent particles Within it (sealed undervacuum).

Examples of food products which are preferably packaged under vacuum orin an atmosphere of inert gas are dried eggs, dried milk, bacon,sausage, hamburger patties, butter, margarine, shortenings, coffee, tea,orange juice powder, tomato juice powder, dried potato granules, driedstring beans, dried peas, dried cabbage slices, dried mushrooms, nutmeats, candies, pickles, and so forth.

Instead of an inert gas or together with the inert gas, other fluids canbe introduced into the package prior to sealing. Thus in packaging foodproducts, after the container is exhausted a stream of nitrogen, dry airor the like may be used as a carrier to introduce diverse vapors intothe package. In this manner one may introduce vapors of such agents as:antioxidants, for example, butylated hydroxyanisole,nordihydroguaiaretic acid, propyl gallate, and so forth;enzyme-inactivating agents as sulphur dioxide; flavoring agents asvolatile fruit essences, essential oils, hickory wood smoke, aceticacid, and so forth; fungicides as propylene oxide; etc. In the case ofpackaging hardware or other metallic objects, vapors ofcorrosion-preventing agents may be inserted in the package in the samefashion. Further extensions of these principles will be obvious from theforegoing.

In the preferred modification of this invention, highfrequencyelectrical energy is used for sealing the plastic film package. It isobvious that other sealing techniques can be used. For example, sealingblade 16 may beprovided with internal coils heated by passage of anelectrical current whereby the blade becomes hot and the sealing isetfectuated simply by applying thermal heating during the phase whenblade 16 and anvil 15 are in engagement.

For rapid sealing of packages on the device of this invention it ispreferred that there be provided rapidacting mechanisms for actuatingthe step-wise closing of jaw 2, connection of tube 23 to the vacuumsource, connection of tube 23 to the fluid source for adding fluid tothe package, activating the high frequency electrical supply forsealing, and opening jaw 2. To this end there may be provided a seriesof push-button switches which operate through relays to activate thevarious valves and switches to accomplish the proper series ofactivities. Devices of this type are purchasable on the open market andneed not be described further herein.

To prevent adhesion of the plastic film to anvil 15 and sealing blade 16it is usually desirable that these members be covered with an thin filmof polyfluoroethylene or other heat-resistant, non-adhesive, softplastic film.

Having thus described the invention what is claimed is:

1. An apparatus for packaging commodities in a flexible-walled,open-mouth bag while the bag is held in the open atmosphere whichcomprises gas conducting means for withdrawing gases from a filled bag,including a vertically disposed flattened tube, a horizontally-disposed,hollow perforated cylinder connected to the lower end of the tube andextending in a line coincident with the larger cross-sectional diameterof the tube, a pair of perforated generally acorn-shaped hollow cages atthe ends of the cylinder, said cages having a greater diameter than saidcylinder, said gas conducting means being adapted to be inserted intothe mouth of said filled bag, resilient means for pressing the upperwalls of the bag about the said flattened tube to effect a temporarysealing of the bag and means for permanently sealing the walls of thebag at a zone below the position of gas conducting means.

2. A device for packaging commodities in a flexiblewalled, open-mouthcontainer while the container is held in the open atmosphere comprisinga fixed jaw and a jaw movable toward and away from said fixed jaw, saidjaws being adapted to receive therebetween a container having an upperopen end and a lower closed end, a first protuberant element on saidfixed jaw, a second protuberant element on said movable jaw aligned withsaid first protuberent element, said protuberant elements being adaptedto pinch the open end of the container therebetween when said jaws aremoved together, gas conducting means for evacuating the container andintroducing fluid therein, said gas conducting means including avertically-disposed flattened tube, a horizontally-disposed, hollowperforated cylinder connected to the lower end of the tube andperforated hollow cages at the ends of the cylinder having a diametergreater than that of the cylinder, said gas conducting means beingpivotally supported by said fixed jaw and extending downwardly betweensaid jaws and elements, a pair of co-acting sealing members carried bysaid jaws, and means for adjusting said movable jaw between a series ofpositions including a first position wherein the jaws are open and acontainer may be inserted therebetween, a second position wherein thejaws are partly closed and the said protuberant elements co-act to closethe upper end of the container but the sealing members are not inengagement, and a third fully closed position wherein said protuberantelements and sealing members are in engagement.

References Cited in the file of this patent UNITED STATES PATENTS1,437,916 Shelor Dec. 5, 1922 1,437,917 Shelor Dec. 5, 1922 1,675,208Broadhurst June 26, 1928 2,094,753 Ryan et al. Oct. 5, 1937 2,281,187Waters Apr. 28, 1942 2,292,295 Royal Aug. 4, 1942 2,540,120 Jacobs etal. Feb. 6, 1951 2,634,562 Mueller et al Apr. 14, 1953 2,649,234 TauntonAug. 18, 1953 2,672,268 Bower Mar. 16, 1954 2,691,474 Olson Oct. 12,1954 2,751,732 Woppman June 26, 1956

